Health care system delay linked with mortality in patients with STEMI treated with primary PCI

Terkelsen CJ. JAMA. 2010;304:763-771.

Issue: October 2010

Incremental increases in health care system time delays had a direct relationship to increasing mortality rates in patients with STEMI who were treated with primary percutaneous coronary intervention, according to study findings.

The historical follow-up study was based on Danish medical registries, which included patients (n=6,209) with STEMI. The patients were transported by emergency medical service and treated with primary PCI within 12 hours of symptom onset at three high-volume PCI centers in western Denmark between 2002 and 2008. Median follow-up time was 3.4 years.

Researchers obtained the following long-term mortality rates (P<.001): 0 to 60-minute system delay, 15.4%; 61 to 120 minutes, 23.3%; 121 to 180 minutes, 28.1%; and 181 to 360 minutes, 30.8%. Multivariable analysis adjusted for other predictors of mortality showed system delay was independently associated with mortality (per 1-hour delay, adjusted HR=1.10; 95% CI, 1.04-1.16), as were its components, pre-hospital system delay and door-to-balloon delay.

“Health care system delay is valuable as a performance measure when patients with STEMI are treated with primary PCI because it is associated with mortality, it constitutes the part of treatment delay modifiable by the health care system in the acute phase, and it applies to patients field-triaged directly to the PCI center as well as to patients transferred from local hospitals,” researchers wrote in the concluding statement of the study. “Increased focus on the total health care system delay may optimize triage of patients with STEMI and may be the key to further improving survival of these patients.”

We have to be careful about causality. It’s not clear that they accounted for all confounders. Some of the sickest people, for a variety of reasons, may take the longest, and they are not actually accounting for it. To me, the real question is: “When did the symptoms start to show up?” The problem is you cannot measure that accurately. Nevertheless, I think that the idea that door-to-balloon time is all that counts is not correct, and this study improves our thinking on that.

– William Weintraub, MD

Cardiology Today Editorial Board

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